Thank you for your email.* We have not tested the Feather with the Seido extended battery attached to the phone.* If the battery alters the form factor of the phone, we would assume that the case would not fit since the Feather is a hard case which is designed to fit the Storm perfectly.* We hope this helps!* If you have any further questions or concerns feel free to contact us.*

Thank you for your email.* We have not tested the Feather with the Seido extended battery attached to the phone.* If the battery alters the form factor of the phone, we would assume that the case would not fit since the Feather is a hard case which is designed to fit the Storm perfectly.* We hope this helps!* If you have any further questions or concerns feel free to contact us.*

Kind Regards,*
Customer Service Team

I figured as much...Check out seido for a form fitting case, they made the battery, see what you can find there.